I recommend St Andrews. Amazing beach, golf, historic university, abbey, castle. Good shops/ cafes/ restaurants. Only 1 1/4 hrs from Edinburgh www.standrews.co.uk/things-to-do-in-st-andrews/sports-leisure/craigtoun-country-park/ Craigtoun is great for a 4 yr old- little train, trampolines, rowing boats, loads of open space to run around too. Also in the area are Cupar Deer park, great coastal walks, loads of lovely fishing villages such as Pittenweem and Crail, award winning fish and chips....

How about Lochgoilhead. Drimsynie holiday park is nice, with leisure facilities on site. Good mix of mountains and sea loch. 15 minute drive to Arrochar, another 5 to loch lomond, about 30 mins to Inverary...loads to see.

Basically we don't have long enough to do everything that we would love to do. Will probably have to restrict the distance to half a day's driving from Edinburgh, possibly a bit further. Walking, hiking (although restricted with a four year old), swimming, some culture.